The desire to look young and healthy is universal. The primary attributes of the young and healthy-looking skin are evenness of the skin color and texture. Age spots and other skin hyperpigmentation are undesirable. In many parts of the world, consumers also want to lighten their background skin color. Accordingly, there is a need for commercially feasible, effective skin care compositions, especially skin lightening products.
Various compositions comprising some substituted diamines or related structures have been described, for example in EP 2193779 (Cognis); WO 2005/016895 (KIM); WO 2008/009860 (L'Oreal); Hirota et al., U.S. Pat. No. 4,412,943; EP 0653208 (Pfizer, Inc.); Dowell et al., U.S. Pat. No. 5,393,519; Winchell et al., US 2001/0041170; Chassot et al., US 2003/0172471; DE 20110356 (Wella AG); Walton, US 2005/0220832; Wagner et al., US 2009/0010860; WO 2008/101692 (Beiersdorf AG); WO 2008/129188 (L'Oreal); EP 0922 447 (Beiersdorf AG).